STOEMS, HURRICANES, AND TYPHOONS. 423 



against the hands of a watch ; but when the wind is north, it is, 

 in the case supposed, travelling south at the rate of 20 miles an 

 hour around the storm, while the progressive movement of the 

 storm itself is north at the rate of 20 miles an hour. One motion 

 exactly cancels the other, and there is, therefore, a line of calm 

 and light, or moderate or not so heavy winds on one side of the 

 centre, while on the other side there is a line of maximum 

 violence ; in other words, in every travelling cyclone the wind 

 blows harder on one side than the other. This is the case in 

 both hemispheres ; and by handling these moving diagrams for 

 illustration, the navigator will soon become familiar with the 

 various problems for determining tlieoretically the direction of 

 the vortex, the course it is travelling, its distance, etc. There- 

 fore, when it is optional with the navigator to pass the storm on 

 either side, he should avoid the heavy side. These remarks 

 apply to both hemispheres. 



793. The rainy quadrant of a cyclone. Captain Toynbee asks if 

 it rains more in one quarter of a cyclone than another ? In 

 cyclones that travel fast, I suppose there would be most rain in 

 the after quarter ; with those that have little or no progressive 

 motion, I conjecture that the rainy quarter, if there be one, 

 would depend upon the quarter whence that wind comes that 

 brings most rain. The rain in a "cyclone is supposed to come 

 from the moisture of that air which has blown its round and 

 gone up in the vortex ; then it expands, grows cool, and con- 

 denses its vapour, which spreads out at top like a great mushroom 

 in the air, the liberated heat adding fury to the storm. 



794. Erroneous theories. — Such, briefly stated, are the two 

 theories. They appear to me, from such observation and study 

 as I have been able to bestow, to be neither of them wholly 

 right or altogether wrong. Both are instructive, and the sug- 

 gestions of one will, in many instances, throw light upon the 

 facts of the other. That rotary storms do frequently occur at 

 .sea we know, for vessels have sometimes, while scudding before 

 the wind in them, sailed round and round. The United States 

 brig " Perry" did this a few years ago in the West Indies ; and 

 so did the " Charles Heddle " in the East Indies : she went round 

 and round a cyclone five times. 



795. The icind in a true cyclone hloics in spirals. — From such ob- 

 servations as I have been able to obtain upon the subject, I am 

 nduced to believe, with Thorn, that the wind in a cyclone does 



